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Clinical Thermometer
Measuring Temperature
Have you seen a thermometer? Recall that when you or someone else in your family had a fever, the temperature was measured by a thermometer. The thermometer that measures our body temperature is called a Clinical thermometer. Hold the thermometer in your hand and examine it carefully. If you do not have a thermometer, request a friend to share it with you. A clinical thermometer looks like the one shown in Fig. 4.2.
Fig4.2 A clinical thermometer
A clinical thermometer consists of a long, narrow, uniform glass tube. It has a bulb at one end. This bulb contains mercury. Outside the bulb, a small shining thread of mercury can be seen. If you do not see the mercury thread, rotate the thermometer a bit till you see it.
You will also find a scale on the thermometer. The scale we use is the celsius scale, indicated by °C.
A clinical thermometer reads temperature from 35°C to 42°C.
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Reading a Thermometer Activity 4.2
Activity 4.2:
Reading a Thermometer
Let us learn how to read a thermometer. First, note the temperature difference indicated between the two bigger marks. Also, note down the number of divisions (shown by smaller marks) between these marks. Suppose the bigger marks read one degree and there are five divisions between them. Then, one small division can read \(\frac{1}{5}\, = \,{0.2^0}C\)
Precautions to be observed while using a clinical thermometer The thermometer should be washed before and after use, preferably with an antiseptic solution.
Ensure that before use the mercury level is below 35°C.
Read the thermometer keeping the level of mercury along the line of sight. (See Fig. 4.3).
Handle the thermometer with care. If it hits against some hard object, it can break.
Don’t hold the thermometer by the bulb while reading it.
Wash the thermometer, preferably with an antiseptic solution. Hold it firmly and give it a few jerks. The jerks will bring the level of mercury down. Ensure that it falls below 35°C. Now place the bulb of the thermometer under your tongue. After one minute, take the thermometer out and note the reading. This is your body temperature. The temperature should always be stated with its unit, °C.
What did you record as your body temperature?
Fig. 4.3 Correct method of reading a clinical thermometer
The normal temperature of the human body is 37°C. Note that the temperature is stated with its unit.
Let us try to assure Paheli that there is nothing wrong with her.
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Reading a Thermometer Activity 4.3
Activity 4.3:
Measure the body temperature of some of your friends (at least 10) with a clinical thermometer. Record your observations as in Table 4.2.
Name
Temperature (°C)
Is the body temperature of every person 37°C?
The temperature of every person may not be 37°C. It could be slightly higher or slightly lower. Actually, what we call normal temperature is the average body temperature of a large number of healthy persons.
The clinical thermometer is designed to measure the temperature of the human body only. The temperature of the human body normally does not go below 35oC or above 42oC. That is the reason that this thermometer has the range 35oC to 42oC.
CAUTION Do not use a clinical thermometer for measuring the temperature of any object other than the human body. Also, avoid keeping the thermometer in the sun or near a flame. It may break.